Pseudechiniscus suillus, (EHRENBERG, 1853) SENSU

PSEUDECHINISCUS SUILLUS ( EHRENBERG, 1853) SENSU View in CoL STRICTO

( TABLE 4, FIGS 3–5 View Figure 3 View Figure 4 View Figure 5 )

Material examined: Forty-five females ( neotype and 44 neoparatypes) mounted on microscope slides in Hoyer’s medium, ten females prepared for SEM and 11

females prepared for barcoding (exoskeletons mounted in Hoyer’s medium as vouchers).

Redescription: animals (measurements and statistics in Table 4)

Females: Body ( Fig. 4 View Figure 4 ) yellow-orange in living specimens (transparent after mounting), eyes black after mounting. Apart from the head appendages [cirri interni and externi and spherical or slightly elongated cephalic papillae (secondary clava)], only lateral cirrus A present [with finger-like clava near the base (primary clava)] ( Fig. 4A, B View Figure 4 ). Cephalic papillae smaller than primary clava.

Dorsal plates with small hemispherical granules/ upper ends of cuticular pillars (dots in LM) 0.3–0.7 μm in diameter, densely (spaces between granules 0.3– 1.1 μm) and uniformly distributed and not joined by striae ( Fig. 5B View Figure 5 ). Granules/upper ends of cuticular pillars are slightly larger in the centre of the plates.

Dorsal plates typical for the genus Pseudechiniscus [single cephalic plate (cp), neck plate (np), scapular plate (scp), median plates (m1, m2, m3), paired segmental plates I and II (s1, s2), pseudosegmental plate (psp) and the caudal plate (cap), see ‘Dorsal and ventral plates and sculpture’ above] well developed. The cp facetted (with W-shaped pattern) divided into five parts ( Fig. 4A View Figure 4 , empty arrowhead). The scp divided by a transversal fold, which forms a long, narrow stripe in the posterior part of the plate. This narrow stripe is often divided by three longitudinal folds, resulting in four plate parts/subplates ( Fig. 4A, B View Figure 4 ). Besides, the entire scp is divided by a median longitudinal fold into two parts ( Fig. 4A, B View Figure 4 , empty arrow). Additionally, lateral portions of the scp appear to be detached from the dorsal plate, forming small plate-like structures separated from the scp by a thin, bright stripe ( Fig. 4A View Figure 4 ). Plates m1 and m2 are divided in two portions by a transverse fold; plate m3 is undivided ( Fig. 4A, B View Figure 4 , filled indented arrowheads). Laterally to the median plates, lateral intersegmental plates (lip) are present. On plates s1 and s2, darker stripes (folds in SEM) are also visible ( Fig. 4A View Figure 4 , filled arrow). The psp is divided by a longitudinal fold. Posterior margin of psp is straight, i.e. without projecting teeth or spines ( Fig. 4A, B View Figure 4 , empty indented arrowheads). The cap is concave with two Y-shaped bifurcated ridges ( Fig. 4A, B View Figure 4 , filled arrowhead). Ventral cuticle with tiny granulation (formed by dense granules/upper ends of cuticular pillars, 0.2–0.4 μm) forming a unique pattern ( Figs 3 View Figure 3 , 4C, D View Figure 4 , 5C View Figure 5 ). Ventral patches of granulation present, but most of them poorly marked and visible sometimes as a smooth areas almost without granulation (if granulation is present it is 0.3–0.5 μm in diameter, spaces between granules 0.2–0.3 μm), with configuration PG:I-II-III-IV-VI-VIII

g

( Figs 3 View Figure 3 , 4C, D View Figure 4 ). The female gonopore with the typical six-petal rosette ( Fig. 4C, D View Figure 4 , asterisks).

The outer cuticle on legs I–III has round patches of granulation (with larger granules but sparser in the centre and smaller and denser in peripheral parts); on legs IV, uniform wide stripes of granulation (slightly larger in the centre of these stripes) ( Fig. 5D–F View Figure 5 ). Triangular spine on leg I absent, instead a small papilla-like structure present, but very hardly visible under LM ( Fig. 5A View Figure 5 ). Dentate collar on leg IV absent. A finger-like papilla on leg IV present ( Fig. 5E View Figure 5 , filled arrow). External claws of all legs smooth, internal with spurs directed downwards ( Fig. 5F View Figure 5 ).